To remove a person from your friend's list in a social network, be it virtual or real. This depends on one thing: the so-called friend has been a real Judas, a bane rather than a boon and someone who has a negative vibe around them. Just like lice or any other parasitic insect, they suck the essence of life out of you. So to remove them would mean to delouse them

He was spreading a lot of shit about me on Facebook, so I deloused him and some of my friends followed suit.